Measurement of an analyte with a cartridge

ABSTRACT

A method of performing an optical measurement of an analyte in a processed biological sample using a cartridge is provided. The cartridge is operable for being spun around a rotational axis. The method comprises: placing the biological sample into a sample inlet; controlling the rotational rate of the cartridge to process a biological sample into the processed biological sample using a fluidic structure; controlling the rotational rate of the cartridge to allow the processed biological sample to flow from the measurement structure inlet to an absorbent structure via a chromatographic membrane, and performing an optical measurement of a detection zone on the chromatographic membrane with an optical instrument. An inlet air baffle reduces evaporation of the processed biological sample from the chromatographic membrane during rotation of the cartridge.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/EP2017/059037, filed 13 Apr. 2017, which claims the benefit ofEuropean Patent Application No. 16165415.7, filed 14 Apr. 2016, thedisclosures of which are hereby incorporated herein by reference intheir entirety.

TECHNICAL FIELD

The present disclosure relates to analytical test devices for biologicalsamples, in particular to the design and use of rotatable cartridges forperforming a measurement of a biological sample.

BACKGROUND

Two classes of analysis systems are known in the field of medicalanalysis: wet analysis systems, and dry-chemical analysis systems. Wetanalysis systems, which essentially operate using “wet reagents” (liquidreagents), perform an analysis via a number of required step such as,for example, providing a sample and a reagent into a reagent vessel,mixing the sample and reagent together in the reagent vessel, andmeasuring and analyzing the mixture for a measurement variablecharacteristic to provide a desired analytical result (analysis result).Such steps are often performed using technically complex, large,line-operated analysis instruments, which allow manifold movements ofparticipating elements. This class of analysis system is typically usedin large medical-analytic laboratories.

On the other hand, dry-chemical analysis systems operate using “dryreagents” which are typically integrated in a test element andimplemented as a “test strip”, for example. When these dry-chemicalanalysis systems are used, the liquid sample dissolves the reagents inthe test element, and the reaction of sample and dissolved reagentresults in a change of a measurement variable, which can be measured onthe test element itself. Above all, optically analyzable (in particularcolorimetric) analysis systems are typical in this class, in which themeasurement variable is a color change or other optically measurablevariable. Electrochemical systems are also typical in this class, inwhich an electrical measurement variable characteristic for theanalysis, in particular an electrical current upon application of adefined voltage, can be measured in a measuring zone of the test elementusing electrodes provided in the measuring zone.

The analysis instruments of the dry-chemical analysis systems areusually compact, and some of them are portable and battery-operated. Thesystems are used for decentralized analysis (also called point-of-caretesting), for example, at resident physicians, on the wards of thehospitals, and in so-called “home monitoring” during the monitoring ofmedical-analytic parameters by the patient himself (in particular bloodglucose analysis by diabetics or coagulation status by warfarinpatients).

In wet analysis systems, the high-performance analysis instruments allowthe performance of more complex multistep reaction sequences (“testprotocols”). For example, immunochemical analyses often require amultistep reaction sequence, in which a “bound/free separation”(hereafter “b/f separation”), i.e., a separation of a bound phase and afree phase, is necessary. According to one test protocol, for example,the sample can first be brought in contact with a specific bindingreagent for the analyte which is immobilized onto a surface. This can beachieved for example by mixing the sample with beads comprising surfaceswith such immobilized reagents or transporting the sample over surfacesor through porous matrices wherein the surfaces or the porous matricescomprise coatings of the immobilized reagents. A marking reagent cansubsequently be brought in contact with this surface in a similar mannerto mark the bound analyte and allow its detection. To achieve a moreprecise analysis, a subsequent washing step is often performed, in whichunbound marking reagent is at least partially removed. Numerous testprotocols are known for determining manifold analytes, which differ inmanifold ways, but which share the feature that they require complexhandling having multiple reaction steps, in particular also a b/fseparation possibly being necessary.

Test strips and similar analysis elements normally do not allowcontrolled multistep reaction sequences. Test elements similar to teststrips are known, which allow further functions, such as the separationof red blood cells from whole blood, in addition to supplying reagentsin dried form. However, they normally do not allow precise control ofthe time sequence of individual reaction steps. Wet-chemical laboratorysystems offer these capabilities, but are too large, too costly, and toocomplex to handle for many applications.

To close these gaps, analysis systems have been suggested which operateusing test elements which are implemented in such a manner that at leastone externally controlled (i.e., using an element outside the testelement itself) liquid transport step occurs therein (“controllable testelements”). The external control can be based on the application ofpressure differences (overpressure or low-pressure) or on the change offorce actions (e.g., change of the action direction of gravity byattitude change of the test element or by acceleration forces). Theexternal control can be performed by centrifugal forces, which act on arotating test element as a function of the velocity of the rotation.

Analysis systems having controllable test elements are known andtypically have a housing, which comprises a dimensionally-stable plasticmaterial, and a sample analysis channel enclosed by the housing, whichoften comprises a sequence of multiple channel sections and chambersexpanded in comparison to the channel sections lying between them. Thestructure of the sample analysis channel having its channel sections andchambers is defined by profiling of the plastic parts. This profiling isable to be generated by injection molding techniques or hot stamping.Microstructures, which are generated by lithography methods,increasingly being used more recently, however.

Analysis systems having controllable test elements allow theminiaturization of tests which have only been able to be performed usinglarge laboratory systems. In addition, they allow the parallelization ofprocedures by repeated application of identical structures for theparallel processing of similar analyses from one sample and/or identicalanalyses from different samples. It is a further advantage that the testelements can typically be produced using established production methodsand that they can also be measured and analyzed using known analysismethods. Known methods and products can also be employed in the chemicaland biochemical components of such test elements.

In spite of these advantages, there is a further need for improvement.In particular, analysis systems which operate using controllable testelements are still too large. The most compact dimensions possible areof great practical significance for many intended applications.

BRIEF SUMMARY

It is against the above background that the embodiments of the presentdisclosure provide certain unobvious advantages and advancements overthe prior art. In particular, the inventors have recognized a need forimprovements in methods for measurement of an analyte with a cartridge.

In accordance with one embodiment of the present disclosure, a method ofperforming an optical measurement of an analyte in a processedbiological sample using a cartridge is provided, wherein the cartridgeis operable for being spun around a rotational axis. The cartridgecomprises: a support structure comprising a front face; a fluidicstructure for processing a biological sample into the processedbiological sample, wherein the fluidic structure comprises a sampleinlet for receiving the biological sample; and a measurement structurerecessed from the front face, wherein the measurement structurecomprises a chromatographic membrane, wherein the measurement structurecomprises a measurement structure inlet connected to the fluidicstructure to receive the processed biological sample, wherein themeasurement structure comprises an absorbent structure, wherein thechromatographic membrane extends from the measurement structure inlet tothe absorbent structure, wherein the chromatographic membrane comprisesa detection zone, wherein the measurement structure comprises an inletair baffle connected to the front face. The method further comprises:placing the biological sample into the sample inlet; controlling therotational rate of the cartridge to process the biological sample intothe processed biological sample using the fluidic structure; controllingthe rotational rate of the cartridge to allow the processed biologicalsample to flow from the measurement structure inlet to the absorbentstructure via the chromatographic membrane, wherein the inlet air bafflereduces the evaporation of the processed biological sample duringrotation of the cartridge; and performing the optical measurement of thedetection zone with an optical instrument.

In accordance with another embodiment of the present disclosure, acartridge for an automatic analyzer is provided, wherein the cartridgeis operable for being spun around a rotational axis. The cartridgecomprises: a support structure, wherein the support structure comprisesa front face; a fluidic structure for processing a biological sampleinto a processed biological sample, wherein the fluidic structurecomprises a sample inlet for receiving the biological sample; and ameasurement structure recessed from the front face, wherein themeasurement structure comprises a chromatographic membrane, wherein themeasurement structure comprises a measurement structure inlet connectedto the fluidic structure to receive the processed biological sample,wherein the measurement structure comprises an absorbent structure,wherein the chromatographic membrane extends from the measurementstructure inlet to the absorbent structure, wherein the measurementstructure comprises an inlet air baffle connected to the front face.

In accordance with yet another embodiment of the present disclosure, amedical system is provided, wherein the medical system comprises acartridge as described herein, wherein the medical system furthercomprises an automatic analyzer configured for receiving the at leastone cartridge, wherein the automatic analyzer comprises a cartridgespinner, an optical instrument, and a controller configured to controlthe automatic analyzer, wherein the controller is configured for:controlling the rotational rate of the cartridge to process thebiological sample into the processed biological sample using the fluidicstructure; controlling the rotational rate of the cartridge to allow theprocessed biological sample to flow across the fluidic membrane from themeasurement structure inlet to the absorbent structure via thechromatographic membrane, wherein the inlet air baffle reduces theevaporation of the buffer solution;

and performing the optical measurement of the detection zone with theoptical instrument.

These and other features and advantages of the embodiments of thepresent disclosure will be more fully understood from the followingdescription in combination with the drawings and the accompanyingclaims. It is noted that the scope of the claims is defined by therecitations therein and not by the specific discussion of features andadvantages set forth in the present description.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of the embodiments of the presentdisclosure can be best understood when read in conjunction with thefollowing drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 shows an example of a cartridge;

FIG. 2 shows a cross sectional view of the cartridge of FIG. 1;

FIG. 3 shows an alternative cross sectional view of the cartridge ofFIG. 1;

FIG. 4 shows an alternative example of a cartridge;

FIG. 5 shows a cross sectional view of the cartridge of FIG. 4;

FIG. 6 shows an alternative example of a cartridge;

FIG. 7 shows an alternative cross sectional view of a cartridge;

FIG. 8 shows an alternative cross sectional view of a cartridge;

FIG. 9 shows an alternative cross sectional view of a cartridge;

FIG. 10 shows an alternative cross sectional view of a cartridge;

FIG. 11 shows an example of a medical system; and

FIG. 12 shows a flow chart which illustrates a method of operating themedical system of FIG. 11.

Skilled artisans appreciate that elements in the figures are illustratedfor simplicity and clarity and have not necessarily been drawn to scale.For example, the dimensions of some of the elements in the figures maybe exaggerated relative to other elements to help improve understandingof the embodiments of the present disclosure.

DETAILED DESCRIPTION

A cartridge as used here encompasses also any test element forprocessing a biological sample into a processed biological sample. Thecartridge may include structures or components which enable ameasurement to be performed on the biological sample. A typicalcartridge is a test element as is defined and explained in U.S. Pat. No.8,114,351 B2 and U.S. Patent Application Publication No. 2009/0191643A1, the disclosures of which are hereby incorporated herein byreference. A cartridge as used herein may also be referred to as acentrifugal microfluidic disc, also known as “lab-on-a-disc”, lab-diskor a microfluidic CD.

A biological sample as used herein encompasses as chemical productderived, copied, replicated, or reproduced from a sample taken from anorganism. A blood sample is an example of a biological sample that iseither whole blood or a blood product. The blood plasma may beconsidered to be a processed biological sample.

It is understood that references to biological samples and productsbelow and in the claims may be modified such that they refer to bloodsamples and/or blood products.

In accordance with one embodiment, the present disclosure provides for amethod of performing an optical measurement of an analyte in a processedbiological sample using a cartridge. The cartridge is operable for beingspun around a rotational axis. The cartridge comprises a supportstructure comprising a front face. The cartridge further comprises afluidic structure for processing a biological sample into the processedbiological sample. The fluidic structure comprises a sample inlet forreceiving the biological sample.

The cartridge further comprises a measurement structure recessed fromthe front face. This may be alternately worded as the measurementstructure is located below the front face. The measurement structurecomprises a chromatographic membrane.

The chromatographic membrane may be referred to as a capillary-activezone. In one embodiment, the capillary-active zone comprises a porous,absorbent matrix. In one embodiment of the test element according to thedisclosure, the second end of the capillary-active zone near to the axisadjoins a further absorbent material or an absorbent structure such thatit can take up liquid from the capillary-active zone. Thecapillary-active zone and the further absorbent material typicallyslightly overlap for this purpose. The further material or the furtherabsorbent structure serve on the one hand, to assist the suction actionof the capillary-active zone and in particular of the porous, absorbentmatrix and, on the other hand, serve as a holding zone for liquid whichhas already passed through the capillary-active zone. In this connectionthe further material can consist of the same materials or differentmaterials than the matrix. For example, the matrix can be a membrane andthe further absorbent material can be a fleece or a paper. Othercombinations are of course equally possible.

The measurement structure further comprises a measurement structureinlet connected to the fluidic structure to receive the processedbiological sample. The measurement structure further comprises anabsorbent structure. The absorbent structure is nearer to the rotationalaxis than the capillary-active zone. In some examples, the absorbentstructure may support the complete transport of the processed biologicalsample across or through the capillary-active zone and may also serve asor be a waste-fleece by binding the processed fluids and/or additionalfluids like washing buffers, thus avoiding their leakage and therebycontamination of the instrument or user.

The chromatographic membrane extends from the measurement structureinlet to the absorbent structure. The absorbent structure may beabsorbent and therefore fluids or liquids that are placed in themeasurement structure inlet may wick to the absorbent structure. Thechromatographic membrane comprises a detection zone. The measurementstructure comprises an inlet air baffle connected to the front face. Anair baffle as used herein is a mechanical structure that is used torestrict the flow of air or other gas. The inlet air baffle serves as avent to the atmosphere surrounding the cartridge to the chromatographicmembrane.

The method comprises placing the biological sample into the sampleinlet. The method further comprises controlling the rotational rate ofthe cartridge to process the biological sample into the processedbiological sample using the fluidic structure. In different examplesthis may take different forms. For example, the biological sample may bediluted, or it may be mixed with other chemicals which change thebiological sample chemically or the biological sample may be mixed withantibodies that react with the analyte and provide markers which canthen be layered on the chromatographic membrane. The method furthercomprises controlling the rotational rate of the cartridge to allow theprocessed biological sample to flow from the measurement structure inletto the absorbent structure via the chromatographic membrane.

The absorbent structure serves on the one hand, to assist the suctionaction of the chromatographic membrane or capillary-active zone and inparticular of the porous, absorbent matrix and, on the other hand, serveas a holding zone for liquid which has already passed through thecapillary-active zone. In this connection the further material canconsist of the same materials or different materials than the matrix.For example, the matrix can be a membrane and the further absorbentmaterial can be a fleece or a paper. Other combinations are of courseequally possible.

The air inlet baffle reduces the evaporation of the processed biologicalsample during rotation of the cartridge. The method further comprisesperforming the optical measurement of the detection zone with an opticalinstrument. The optical instrument for example may be a spectrographicinstrument.

This embodiment may be beneficial because the air inlet baffle mayreduce the access of air or the atmosphere surrounding the cartridgewhen it is spun. Reducing the evaporation of the processed biologicalsample may be beneficial in that it may provide for more accuratemeasurements. In other cases, because the evaporation is reduced, thebiological sample may function if a smaller volume is used. In otherexamples the inlet air baffle may provide the benefit that lessadditional fluid needs to be mixed with the biological sample to turn itinto the processed biological sample.

The fluidic structure may contain a reagent zone which contains aconjugate of an analyte binding partner (typically an antibody or animmunologically active antibody fragment capable of analyte binding ifthe analyte is an antigen or hapten, or an antigen or hapten if theanalyte is an antibody) and a label which can be detected directly orindirectly by visual, optical or electrochemical means, wherein theconjugate can be dissolved by the liquid sample. Suitable labels are,for example, enzymes, fluorescent labels, chemiluminescent labels,electrochemically active groups or so-called direct labels such as metalor carbon labels or colored lattices. This zone may also be referred toas the conjugate zone.

The conjugate zone can serve also as a sample application zone or aseparate sample application zone can be located on the test element. Theconjugate zone can, in addition to the conjugate of analyte bindingpartner and label described above, also contain an additional conjugateof a second analyte binding partner (which is in turn typically anantibody or an immunologically active antibody fragment capable ofanalyte binding) and a tagging substance which is itself a partner in abinding pair. The tagging substance can for example be biotin ordigoxigenin and can be used to immobilize a sandwich complex consistingof labelled conjugate, analyte and tagged conjugate in the detectionand/or control zone.

The chromatographic membrane may additionally comprise a detection zonewhich contains a permanently immobilized binding partner (i.e., one thatcannot be detached by the liquid sample) for the analyte or forcomplexes containing the analyte. The immobilized binding partner is inturn typically an antibody or an immunologically active antibodyfragment capable of analyte binding or an antigen or (poly)hapten. Ifone of the above-mentioned tagged conjugates is used which for examplecomprises biotin or digoxigenin together with an analyte bindingpartner, the immobilized binding partner can also be streptavidin orpolystreptavidin and an anti-digoxigenin antibody.

Finally, there may also be a control zone in or on the chromatographicmembrane which contains a permanently immobilized binding partner forthe conjugate of analyte binding partner and label for example in theform of an immobilized polyhapten which acts as an analyte analogue andis able to bind the analyte binding partner from the labelled conjugate.The control zone may additionally contain one or more permanentlyimmobilized binding partner(s) for the analyte or for complexescontaining the analyte. The latter binding partners can be selected fromthe same compounds which were described above in connection with theimmobilized binding partners of the detection zone. These immobilizedbinding partners in the detection zone and in the control zone aretypically identical. They may, however, also be different for example inthat a binding partner for a biotin-tagged conjugate (hence, e.g.,polystreptavidin) is immobilized in the detection zone and ananti-analyte antibody is immobilized in the control zone in addition tothe polyhapten. In the latter case the anti-analyte antibody that isadditionally immobilized in the control zone should be directed against(another) independent epitope and thus one that is not recognized by theconjugate antibodies (biotin-tagged conjugate and labelled conjugate).

In another embodiment, the air inlet baffle is closer to the rotationalaxis than the measurement structure inlet. The inlet baffle isconfigured for regulating a flow of air over the measurement structureduring rotation of the cartridge about the rotational axis. Thisembodiment may be beneficial because the controlled airflow may allowfor both improved visibility of the chromatographic membrane (duringmeasurement) and reduced evaporation from the chromatographic membrane.In contrast, FIG. 2 of U.S. Patent Application Publication No. US2009/0191643 A1 shows two small vent openings which only function toenable the fluidic structures to be filled with samples or washingliquid.

In another embodiment, the absorbent structure is a waste fleece.

In another embodiment, the chromatographic membrane can contain one ormore zones containing immobilized reagents.

Specific binding reagents for example specific binding partners such asantigens, antibodies, (poly) haptens, streptavidin, polystreptavidin,ligands, receptors, nucleic acid strands (capture probes) are typicallyimmobilized in the capillary-active zone and in particular in theporous, absorbent matrix. They are used to specifically capture theanalyte or species derived from the analyte or related to the analytefrom the sample flowing through the capillary-active zone. These bindingpartners can be present immobilized in or on the material of thecapillary-active zone in the form of lines, points, patterns or they canbe indirectly bound to the capillary-active zone, e.g., by means ofso-called beads. Thus, for example, in the case of immunoassays oneantibody against the analyte can be present immobilized on the surfaceof the capillary-active zone or in the porous, absorbent matrix whichthen captures the analyte (in this case an antigen or hapten) from thesample and also immobilizes it in the capillary-active zone such as,e.g., the absorbent matrix. In this case the analyte can be madedetectable for example by means of a label that can be detectedvisually, optically or fluorescence-optically by further reactions, forexample by additionally contacting it with a labelled bindable partner.

In another embodiment, the fluidic structure contains a first specificbinding partner of the analyte with a detectable label and a secondspecific binding partner with a capture label. These both form a bindingcomplex with the analyte. This may consist of a first specific bindingpartner, a second specific binding partner and an analyte. This mayadditionally provide for a measurement structure within the immobilizedbinding partner specific to the capture label of the second specificbinding partner.

In another embodiment, the detection is fluorescence-based.

In another embodiment, the label is particle-based fluorescent label.

In another embodiment, the chromatographic membrane contains an opticalcalibration zone. The optical calibration zone may for example be aregion on the measurement structure which contains a defined amount ofthe immobilized label and provides a means for checking if the optics ofthe instrument is functioning properly and if not, to calibrate itadequately. In other embodiments, the optical calibration zone islocated at different locations on the test element.

In another embodiment, the measurement structure contains a reagent andflow control zone. This may provide for a means of checking if thecartridge is functioning properly in terms of reagents andimmunochromatography. There may be for example two different controlzones, a reagent/flow-control and an optical calibration zone asinstrument control zone for correcting the intensity of the radiation orexcitation source when an optical measurement is made.

In another embodiment, the cartridge is disk-shaped or at leastpartially disk-shaped.

In another embodiment, the cartridge may have an outer edge which fitswithin a circle drawn around the rotational axis.

In another embodiment, the cartridge has an outer edge. The outer edgemay have a portion or portions that are circularly symmetric around therotational axis.

In another embodiment, the method further comprises placing the buffersolution at the measurement structure inlet after controlling therotational rate of the cartridge to allow the processed biologicalsample to flow from the measurement structure inlet to the absorbentstructure via the chromatographic membrane. The method further comprisescleaning or washing the chromatographic membrane by controlling therotational rate of the cartridge to allow the buffer solution to flowfrom the measurement structure inlet to the absorbent structure via thechromatographic membrane before performing the optical measurement. Theuse of the buffer solution may be beneficial because it may provide fora more accurate and reproducible measurement of the analyte. The use ofthe cartridge with the inlet air baffle may further increase thisbenefit as it may reduce the evaporation of the buffer solution inaddition to reducing the evaporation of the biological sample. This mayallow less buffer solution to be used and may also provide for a morecontrolled transport of the buffer solution across the chromatographicmembrane to the absorbent structure.

In another aspect, the present disclosure provides for a cartridge foran automatic analyzer. The cartridge is operable for being spun about arotational axis. The cartridge comprises a support structure. Thesupport structure comprises a front face. The cartridge furthercomprises a fluidic structure for processing a biological sample into aprocessed biological sample. The fluidic structure comprises a sampleinlet for receiving the biological sample. The cartridge furthercomprises a measurement structure recessed from the front face. Themeasurement structure comprises a chromatographic membrane. Themeasurement structure comprises a measurement structure inlet connectedto the fluidic structure to receive the processed biological sample. Themeasurement structure comprises an absorbent structure. Thechromatographic membrane extends from the measurement structure inlet tothe absorbent structure. The measurement structure comprises an airinlet baffle connected to the front face.

In another embodiment, the air inlet baffle is closer to the rotationalaxis than the measurement structure inlet. This embodiment may have thebenefit of enabling the control of an airflow across the chromatographicmembrane.

In another embodiment, there is a gap between the air inlet baffle andthe measurement structure inlet. This embodiment may have the benefit ofbetter controlling the flow of air over the chromatographic membrane.

In another embodiment, the gap is over the chromatographic membrane.This embodiment may have the benefit of reducing airflow through themeasurement structure inlet. This is because it may be beneficial toreduce airflow through the measurement structure inlet to reduceevaporation.

In another embodiment, the inlet baffle is configured for regulating aflow of air over the measurement structure during rotation of thecartridge about the rotational axis. This embodiment may have thebenefit of providing precise control of the evaporation rate of fluidfrom the chromatographic membrane at the same time that the visibilityof the chromatographic membrane is controlled. For example, if there isa static cover over the chromatographic membrane, the relationshipbetween how much fluid is evaporated from the chromatographic membraneand the reduction of the condensation on the static cover can becontrolled.

In another embodiment, the air inlet baffle is directly connected to thechromatographic membrane. This may have the benefit of reducingevaporation from the measurement structure inlet.

In another embodiment, the measurement structure inlet and the air inletbaffle are connected via a path entirely over the chromatographicmembrane. This may have the benefit of reducing evaporation from themeasurement structure inlet.

In another embodiment, the measurement structure inlet and the air inletbaffle are disjoint. “Disjoint” as used herein is understood to meanthat the measurement structure inlet and the air inlet baffle are notdirectly connected. They are connected via an air volume over thechromatographic membrane. This may have the benefit of reducingevaporation from the measurement structure inlet.

In another embodiment, the measurement structure inlet is vented via anair volume over the chromatographic membrane. This may have the benefitof reducing evaporation from the measurement structure inlet.

In another embodiment, the measurement structure further comprises astatic cover for covering the chromatographic membrane. The static covercomprises an optically transparent area. The optically transparent areamay be considered to be an optically transparent window or zone also.Optically transparent as used herein encompasses being transparent to atleast a portion of the electromagnetic spectrum which is in the opticalor near optical range. In the context of making the optical measurementusing the cartridge optically transparent could be interpreted as beingoptically transparent at the wavelengths at which the opticalmeasurement is made.

The optically transparent area is fixed in alignment with the detectionzone of the chromatographic membrane. In other words, the opticallytransparent area is not able to move in relation to the detection zoneof the chromatographic membrane. The optically transparent area istherefore immobile in space relative to the chromatographic membrane.The measurement structure further comprises an air outlet baffleconnected to the front face. The measurement structure is vented by theoutlet air baffle and the inlet air baffle. This embodiment may bebeneficial because fluid in the form of the processed biological sampleor even a buffer solution is transported across the chromatographicmembrane. When fluid or liquid is transported across the chromatographicmembrane there may be evaporation of the liquid or fluid which is thendeposited on the inside of the optically transparent area. Having aninlet and outlet air baffle may be beneficial because a small amount oftransported air may reduce the chance that condensation on the opticallytransparent area obstructs the optical measurement of the detectionzone. However, the use of the inlet air baffle and the outlet air bafflerestricts the amount of evaporation in total. A controlled amount of airgoing through the space above the chromatographic membrane and below theoptically transparent area reduces the total amount of evaporation whilestill allowing for enough transport of moisture away from the opticallytransparent area that the optical measurement can still be performed.

In another embodiment, the measurement structure comprises an air volumeformed at least partially by the static cover. The air volume formed bythe static cover is then vented by the inlet air baffle and the outletair baffle. The inlet air baffle and outlet air baffle seek to reduceevaporation from the chromatographic membrane while at the same timeallowing for the transport of moisture away from the opticallytransparent area.

In another embodiment, the detection zone has a detection zone length ina radial direction. That is to say one could draw a line from therotational axis past the detection zone. The detection zone length isthen the length or extension of the detection zone along this radialline. The inlet air baffle has an inlet air baffle length in the radialdirection. The outlet air baffle has an outlet air baffle length also inthe radial direction. The inlet air baffle length and/or the outlet airbaffle length is less than the detection zone length. This embodimentmay be beneficial because the inlet air baffle and the outlet air bafflewhen they are shorter than the detection zone in the radial directionmay provide for effective venting of the air adjacent to the opticallytransparent area.

It is understood that when describing the radial direction, the radialdirection may rotate as a particular structure is measured. For example,the detection zone length may be in a first radial direction that passesthrough the detection zone. The outlet air baffle length may be a secondradial direction that passes through the outlet air baffle. Likewise,the inlet air baffle length may be a length measured in a third radialdirection that passes through the inlet air baffle.

In another embodiment, one of the outlet air baffle and the inlet airbaffle is closer to the rotational axis than the other. In one examplethe outlet air baffle is closer to the rotational axis than the inletair baffle. In the other case, the inlet air baffle is closer to therotational axis than the outlet air baffle. This embodiment may bebeneficial because it may force any air going from the inlet air baffleto the outlet air baffle to follow a path across the opticallytransparent area. This may provide for reduced condensation on theoptically transparent area.

In another embodiment, the detection zone has a detection zone length ina radial direction. The inlet air baffle has an inlet air baffle lengthin the radial direction. The outlet air baffle has an outlet air bafflelength in the radial direction. The inlet air baffle length and/or theoutlet air baffle length is greater than or equal to the detection zonelength. The details of the radial direction, regarding the detectionzone length, the inlet air baffle length, and the outlet air bafflelength discussed in the above embodiment also apply to this embodiment.

In another embodiment, the outlet air baffle and the inlet air bafflemay be the same distance to the rotational axis.

In another embodiment, the inlet air baffle has a first continuallysmooth surface where the inlet air baffle meets the front face and/orwherein the outlet air baffle has a first continually smooth surfacewhere the inlet air baffle meets the front face. The smooth surfacewhere the baffles meet the front face may serve to reduce the amount ofturbulence generated by the inlet and outlet air baffles. This may helpreduce the amount of fluid lost from the chromatographic membranethrough evaporation.

In another embodiment along a circumferential path across the detectionzone the static cover has a first edge and a second edge. Acircumferential path is a path which is circular and is drawn about therotational axis. The first edge is a first distance from thechromatographic membrane along the rotational axis. A distance measurealong the rotational axis is implied herein to mean a distance which ismeasured in a direction parallel to the rotational axis. For example,the first distance is the distance measured from the chromatographicmembrane to the first edge parallel to the rotational axis. Otherreferences to distances along the rotational axis are also to beinterpreted as meaning a distance measured which is parallel to therotational axis.

The second edge is a second distance from the chromatographic membranealong the rotational axis. The first distance is less than the seconddistance. Adjacent to the first edge the front face has a third distancefrom the chromatographic membrane along the rotational axis. The firstdistance is greater than the third distance. At the front face thestatic cover is continually smooth between the first edge and the secondedge. This embodiment may be beneficial because the inlet air baffle isformed where the first edge is. The air inlet baffle at this point formsa scoop-like structure. When the disk is rotated such that the firstedge moves towards the position of the second edge then air is notscooped into the air inlet baffle. The disk for instance may be run inthis direction to reduce the amount of evaporation typically from thechromatographic membrane. When the disk is rotated in the otherdirection about the rotational axis, that is to say the second edge ismoved towards where the first edge currently is, then the first edgebeing slightly above the front face or above it acts as a scoop thatpreferentially brings air into the space beneath the opticallytransparent area. This embodiment may offer better management of thetrade-off between keeping the optically transparent area clean ofcondensation and also to balance this against the evaporation of fluidfrom the chromatographic membrane.

In another embodiment adjacent to the second edge the front face is afourth distance from the chromatographic membrane along the rotationalaxis. The fourth distance is greater than or equal to the firstdistance. This embodiment may be beneficial because the outlet airbaffle then does not have the effect of scooping air into the spacebeneath the optically transparent area. This may embody the cartridge tohave two different effects of air passing through or beyond theoptically transparent area.

In another embodiment, the entire measurement zone is open to the frontface via the first air baffle structure along a directed path. In otherwords, the entire measurement zone is able to be exposed to directmeasurement from an optical instrument. There is no opticallytransparent region which shields the measurement zone of thechromatographic membrane in this embodiment. The directed path isparallel to the rotational axis. This embodiment may provide for abetter measurement of the measurement zone using the optical instrument.

In another embodiment, the measurement structure comprises at least oneair pocket adjacent to the chromatographic membrane. The at least oneair pocket is covered by the front face parallel to the rotational axis.This means that if one starts in the air pocket and then traces a pathin a direction parallel to the rotational axis, the front face shieldsor covers the air pocket. The air pocket for instance may be a regionadjacent to the chromatographic membrane which is covered by the frontface. The use of the air pocket may be beneficial because it may help totrap air around the chromatographic membrane and reduce the evaporation.

In another embodiment, the measurement zone is within certain spots orlocations of the chromatographic membrane. The inlet air baffle and theoutlet air baffle may be holes or multiple holes which are located inthe front face in a direction parallel to the rotational axis.

In another embodiment along a circumferential path across the detectionzone the inlet air baffle has a first air baffle edge and a second airbaffle edge where the inlet air baffle meets the front face. The firstair baffle edge and the second air baffle edge for instance may be araised area of the front face which helps to prevent air from reachingthe chromatographic membrane as the cartridge is rotated about therotational axis.

In another embodiment along the rotational axis the first air baffleedge is further from the chromatographic membrane than the second airbaffle edge. This may be beneficial because the first air baffle edgemay be used to disrupt the flow of air to the chromatographic membraneand placing the second air baffle edge closer to the chromatographicmembrane may reduce the amount of turbulence. This may help to reduceevaporation from the chromatographic membrane.

In another embodiment, the front face has an average distance from thechromatographic membrane along the rotational axis. The first air baffleedge and the second air baffle edge are further from the chromatographicmembrane than the front face along the rotational axis. Placing thefirst air baffle edge and the second air baffle edge further away fromthe chromatographic membrane may reduce the amount of evaporation fromthe chromatographic membrane.

The first air baffle edge and the second air baffle edge may also bedescribed as ridges or raised areas adjacent to the chromatographicmembrane. The average distance of the front face may be taken about acircumference or rotational path about the rotational axis.

In another aspect, the present disclosure provides for a medical system.The medical system comprises a cartridge according to any one of thepreceding embodiments. The medical system further comprises an automaticanalyzer configured for receiving the at least one cartridge. Theautomatic analyzer comprises a cartridge spinner, an optical instrument,and a controller configured to control the automatic analyzer.

The controller is configured to control the rotational rate of thecartridge to process the biological sample into the processed biologicalsample using the fluidic structure. The processed biological sample ismixed with the buffer solution. In some examples the automatic analyzermay also place the biological sample into the sample inlet. However, inother examples this may be done by an operator before placing the atleast one cartridge into the automatic analyzer. The controller isfurther configured to control the rotational rate of the cartridge toallow the processed biological sample to flow across the chromatographicmembrane from the measurement structure. The inlet air baffle reducesthe evaporation of the processed biological sample. The controller isfurther configured to control the optical instrument to perform theoptical measurement of the detection zone with the optical instrument.

In another embodiment the medical system comprises the at least onecartridge.

It is understood that one or more of the aforementioned embodimentsand/or examples of the disclosure may be combined as long as thecombined embodiments are not mutually exclusive.

In order that the embodiments of the present disclosure may be morereadily understood, reference is made to the following examples, whichare intended to illustrate the disclosure, but not limit the scopethereof.

Like numbered elements in these figures are either equivalent elementsor perform the same function. Elements which have been discussedpreviously will not necessarily be discussed in later figures if thefunction is equivalent.

FIG. 1 shows a top view of a cartridge 100. The cartridge comprises asupport structure 102. The front face 104 is facing towards the viewerin this view. The cartridge 100 is circular and has an edge 106 that isrotationally symmetric about a rotational axis 108. In this example therotational axis 108 is viewed directly on in this front view. In otherexamples the edge 106 may not be rotationally symmetric about the entireedge 106. There may for example be flat regions which are useful forholding or gripping the cartridge 100. The cartridge 100 comprises afluidic structure 110 which is within the support structure 102. Thefluidic structure 110 may comprise a sample inlet 112. The cartridge 100also comprises a measurement structure 114. The measurement structure114 comprises a measurement structure inlet 116 which has a connection118 to the fluidic structure 110. The sample inlet 112 may be forreceiving a biological sample. The fluidic structure 110 is intended tobe arbitrary and represent a fluidic structure which can be used toprocess the biological sample into a processed biological sample whichcan then be transported via the connection 118 to the measurementstructure inlet 116.

The measurement structure 114 further comprises a chromatographicmembrane 120 which is recessed from the front face 104. The measurementstructure 114 also comprises an absorbent structure 126 which isabsorbent. Fluid placed in the measurement structure inlet 116 will wickthrough or across the chromatographic membrane 120 towards the absorbentstructure 126. There may be antibodies or other reactive chemicalsplaced on the chromatographic membrane 120 within a detection zone 122.Portions of the analyte to be measured may then stick or stay at thedetection zone 122. Other antibodies added with the fluidic structure110 may for instance contain fluorescent markers which may be detectedby an optical instrument. The front face 104 may have an opticallytransparent area 124 above the detection zone 122 such that opticalmeasurements can be performed. In this example there is a static cover134. The optically transparent area 124 is a region of the static cover134.

As fluid is transported across the chromatographic membrane 120 theremay be condensation which builds up on the underside of the opticallytransparent area 124 that is adjacent to the chromatographic membrane120. This may cause condensation which may cause errors or prevent theoptical measurement of the detection zone 122. To prevent this there isan inlet air baffle 128 and an outlet air baffle 130. This enables asmall or reduced amount of air to pass beneath the optically transparentarea 124 to help keep it free from condensation. Above thechromatographic membrane 120 is a portion of the front face 104. Havinga structure such as plastic above the chromatographic membrane 120 helpsto reduce evaporation. This may increase the reproducibility and/orsensitivity of the measurement of the analyte by optical means.

In FIG. 1, it can be seen that the air inlet baffle 128 is closer to therotational axis 108 than the measurement structure inlet 116. In thisFIG. 1 there is a gap 140 between the air inlet baffle 128 and themeasurement structure inlet 116. The measurement structure inlet clearlyprovides for an airflow that is directed away from the measurementstructure inlet 116.

The system illustrated in FIG. 1 is intended to be representative. Theremay also be a system for dispensing a buffer solution to the measurementstructure inlet 116. This is not shown in FIG. 1, but it may bebeneficial that after the processed biological sample has beentransported across the detection zone 122 that a buffer is used to washand help clean the chromatographic membrane 120. This may increase thesensitivity and/or reproducibility of the measurement of the analyte.

The dashed line 132 shows a cross-section which is used to illustrate across-sectional view in FIG. 2.

FIG. 2 shows a cross-sectional view 200 along the dashed line 132 ofFIG. 1. The cross-sectional view 200 shows the support structure 102.The support structure 102 for instance may be molded plastic whichcontains the fluidic structure that is molded. In this FIG. 2, an airvolume 206 between the static cover 134 and the chromatographic membrane122 is shown.

FIG. 3 shows an alternate cross-sectional view 300. The example shown inFIG. 3 is similar to that in FIG. 2 except the surfaces of the inlet airbaffle 128 and the outlet air baffle 130 have been more smoothed toreduce turbulence. The smooth surfaces may reduce the chances ofturbulence forming within the air volume 206. This may further reducethe amount of evaporation from the chromatographic membrane 120. It canbe seen that the inlet air baffle 128 has a first continuously smoothsurface 302. The outlet air baffle 130 has a second continuously smoothsurface 304. The optically transparent area 124 also is shown as havingbeen smoothed.

FIG. 4 shows a modification of the cartridge 100 as shown in FIG. 1. Thestructures shown in FIG. 4 are nearly identical to those shown in FIG. 1except the inlet air baffle 128 and the outlet air baffle 130 areconstructed differently. The dashed line 132′ shows a furthercross-sectional view which is illustrated in FIG. 5.

In the cross-sectional view 500 of FIG. 5 it can be seen that thestructure is nearly identical with what is present in FIG. 2. In thisexample the optically transparent area 124 has been made thicker toreduce airflow through the air volume 206. Also the inlet air baffle 128and the outlet air baffle 130 have been enlarged by placing a chamfer502 in the support structure 102. This may help to further reduceturbulence and reduce evaporation at the chromatographic membrane 120.

FIG. 6 shows a further variant of the cartridge 100. The example shownin FIG. 6 is very similar to the example shown in FIG. 1 except in thiscase the inlet air baffle 128′ has become smaller than is shown inFIG. 1. Likewise, the outlet air baffle 130′ is also smaller than theoutlet air baffle 130 in FIG. 1. In this FIG. 6 can be seen a line 600which is drawn from the rotational axis 108 through the detection zone122. When measured along the line 600, it can be seen that the outletair baffle 130′ and the inlet air baffle 128′ have been made smalleralong the direction 600 than was in previous embodiments. The inlet 128′and the outlet 130′ are now smaller in dimension than the detection zone122. One of the two is also placed closer to the rotational axis 108than the other. Reducing the size of the inlet 128′ and outlet 130′ mayhave the effect of reducing the amount of evaporation from thechromatographic membrane 120. Also their placement can be used to forceair going from the inlet 128′ to the outlet 130′ to follow a particularpath across the optically transparent area 124. In this particularexample the outlet air baffle 130′ is shown as being closer to therotational axis 104 than the inlet air baffle 128′. These two may bereversed. There is again a gap 140 between the air inlet baffle 128′ andthe measurement structure inlet 116.

FIG. 7 shows a further cross-sectional view 700 which is alternate tothose shown in FIGS. 2, 3, and 5. In the example shown in FIG. 7 thereis a static cover 134 which is sloped. The cross-sectional view has theappearance of an air foil. The static cover 134 in this shape has theeffect of either directing air away from the air volume 206 or directingair into it. This can be used to preferentially reduce evaporation fromthe chromatographic membrane 120 or to force a small amount of air intothe air volume 206 to remove or prevent condensation on the underside204. The static cover 134 is part of the front face 104 and is fixed inposition over the chromatographic membrane 120.

The thickness of the static cover 134 varies when measured along thedirection 702. It is possible that this variation in thickness acts as alens for light coming from the chromatographic membrane 120. In somecases, the optical measurement system may have an optical component orlens which compensates for this effect.

In FIG. 7 it can be seen that the static cover 134 has a first edge 704and a second edge 706. The dashed line 702 indicates a directionparallel to the rotational axis. Measured parallel to the rotationalaxis 702 the first edge 704 is a first distance 708 from thechromatographic membrane 120. The second edge 706 is a second distance710 from the chromatographic membrane 120. The distance 708 is smallerthan the distance 710. It can also be seen in this FIG. 7 that the frontface 104 on either side of the static cover 134 has portions which aredifferent distances from the chromatographic membrane 120. Adjacent tothe first edge 704 the front face 104 is a third distance 712 from thechromatographic membrane. The area of the front face 104 adjacent to thesecond edge 706 is a fourth distance 714 from the chromatographicmembrane 120. The distances 708, 710, 712 and 714 are measured parallelto the rotational axis 702. The first edge 704 at least partially formsthe inlet air baffle 128. The second edge 706 forms part of the outletair baffle 130. Placing the first edge 704 above the front face 104causes the inlet air baffle 128 to be like a scoop. When the second edge706 is moved towards the first edge 704 rotationally this causes ascoop-like effect which forces air into the air volume 206. When thecartridge is rotated in the opposite direction such that the first edge704 is moved in the direction of the second edge 706 then the air passesover the outer surface of the static cover 134 more easily. This mayreduce airflow through the air volume 206. And have the effect ofreducing evaporation of a fluid from the chromatographic membrane 120.

FIG. 8 shows a further alternate cross-sectional view 800. In thisexample the static cover 134 is absent. In this example only the inletair baffle 128 is present. The dashed line 702 again marks a directionparallel to the rotational axis. It can be seen that if a line 802 istaken parallel to the rotational axis 702 that there is a directed path802 from the detection zone 122 which is not obstructed by the frontface 104. To the side of the chromatographic membrane is an air pocket804. There is an air pocket 804 on either side of the membrane 120. Apath 806 parallel 702 to the rotational axis from the air pocket 804reaches the front face 104. The effect of the air pockets 804 is to trapair in the space above the chromatographic membrane 120. This reducesthe evaporation of fluid from the chromatographic membrane 120. The openspace above the chromatographic membrane 120 can also be selectivelyplaced above the detection zone 122. This would also eliminate thepotential difficulty caused by condensation on the underside of thestatic cover 134.

FIG. 9 shows a further cross-sectional view 900. Again, like FIG. 8there is a directed path 802 in a direction 702 parallel to therotational axis that exposes the detection zone 122. In this embodiment900 there are no air pockets. Instead there is a first air baffle whichhas a first air baffle edge 902 and a second air baffle edge 904. In thedirection 702 parallel to the rotational axis the first air baffle edge902 is a distance 906 from the chromatographic membrane 120. The frontface is a distance 910 from the chromatographic membrane and the secondair baffle edge 904 is a distance 908 from the chromatographic membrane120. As the cartridge 100 is rotated the first air baffle edge 902disrupts airflow to the chromatographic membrane 120 reducing theevaporation of fluid. In this example the second air baffle edge 904 isshown such that the distance 908 and 910 are equal. In other embodimentsthe distance 908 could be increased such that it is equal to or lessthan the distance 906.

FIG. 10 shows an alternative cross-sectional view 1000. Thecross-sectional view 1000 is similar to that of FIG. 9 except thedistance 908 has been increased such that it is equal to the distance906.

FIG. 11 shows an example of a medical system 1100. The medical system1100 is adapted for receiving a cartridge 100. There is a cartridgespinner 1102 which is operable for rotating the cartridge 100 about therotational axis. The cartridge spinner 1102 has a motor 1104 attached toa gripper 1106 which attaches to a portion of the cartridge 1108. Thecartridge 100 is shown further as having a measurement structure 114.The cartridge 100 can be rotated such that the measurement structure 114goes in front of an optical measurement system 1112 which can performfor example an optical measurement of the quantity of the analyte. Anactuator 1111 is optionally shown in this FIG. 11. It can be used toopen fluid reservoirs in the cartridge 100 or manipulate a dispenser toprovide buffer solution to the cartridge. There may also be additionalactuators or mechanisms for actuating mechanical valves or valveelements on the cartridge if they are present.

The actuator 1111, the cartridge spinner 1102, and the measurementsystem 1112 are shown as all being connected to a hardware interface1116 of a controller 1114. The controller 1114 contains a processor 1118in communication with the hardware interface 1116, electronic storage1120, electronic memory 1122, and a network interface 1124. Theelectronic memory 1130 has machine executable instructions which enablethe processor 1118 to control the operation and function of the medicalsystem 1100. The electronic storage 1120 is shown as containing ameasurement 1132 that was acquired when instructions 1130 were executedby the processor 1118. The network interface 1124 enables the processor1118 to send the measurement 1132 via network connection 1126 to alaboratory information system 1128.

FIG. 12 shows a flowchart, which illustrates a method of operating themedical system of FIG. 11. First in step 1200 the processor 1218controls the cartridge spinner 1202 to control the rotational rate ofthe cartridge 100 to process the biological sample into the processedbiological sample using the fluidic structure. Next in step 1202 theprocessor 1218 further controls the cartridge spinner 1202 to controlthe rotational rate of the cartridge to allow the processed biologicalsample to flow from the measurement structure inlet to the absorbentstructure via the chromatographic membrane 120. During this process theinlet air baffle reduces the evaporation of the processed biologicalsample during rotation of the cartridge. Finally, in step 1204 theprocessor 1218 controls the optical instrument 1212 to perform theoptical measurement of the detection zone.

LIST OF REFERENCE NUMERALS

-   -   100 cartridge    -   102 support structure    -   104 front face    -   106 edge    -   108 rotational axis    -   110 fluidic structure    -   112 sample inlet    -   114 measurement structure    -   116 measurement structure inlet    -   118 connection    -   120 chromatographic membrane    -   122 detection zone    -   124 optically transparent area    -   126 absorbent structure    -   128 inlet air baffle    -   128′ inlet air baffle    -   130 outlet air baffle    -   130′ outlet air baffle    -   132 cross section    -   132′ cross section    -   134 static cover    -   140 gap    -   200 cross sectional view    -   202 cover    -   204 underside of optically transparent area    -   206 air volume    -   300 cross section    -   302 first continually smooth surface    -   304 second continually smooth surface    -   500 cross sectional view    -   502 chamfer    -   600 radial direction    -   700 cross sectional view    -   702 parallel to rotational axis    -   704 first edge    -   706 second edge    -   708 first distance to chromatographic membrane    -   710 second distance to chromatographic membrane    -   712 third distance to chromatographic membrane    -   714 fourth distance to chromatographic membrane    -   800 cross sectional view    -   802 directed path    -   804 air pocket    -   806 path    -   808 air pocket    -   900 cross sectional view    -   902 first air baffle edge    -   904 second air baffle edge    -   906 distance    -   908 distance    -   910 distance    -   1000 cross sectional view    -   1101 automatic analyzer    -   1100 medical system    -   1102 cartridge spinner    -   1104 motor    -   1106 gripper    -   1108 portion of cartridge    -   1111 actuator    -   1112 optical measurement system    -   1114 controller    -   1116 hardware interface    -   1118 processor    -   1120 electronic storage    -   1122 electronic memory    -   1124 network interface    -   1126 network connection    -   1128 laboratory information system    -   1130 executable instructions    -   1132 measurement    -   1200 control the rotational rate of the cartridge to process the        biological sample into the processed biological sample using the        fluidic structure    -   1202 control the rotational rate of the cartridge to allow the        processed biological sample to flow from the measurement        structure inlet to the absorbent structure via the        chromatographic membrane    -   1204 perform the optical measurement of the detection zone with        an optical instrument

What is claimed is:
 1. A method of performing an optical measurement ofan analyte in a processed biological sample using a cartridge, whereinthe cartridge is operable for being spun around a rotational axis,wherein the cartridge comprises: a support structure comprising a frontface; a fluidic structure for processing a biological sample into theprocessed biological sample, wherein the fluidic structure comprises asample inlet for receiving the biological sample; and a measurementstructure recessed from the front face, wherein the measurementstructure comprises a chromatographic membrane, wherein the measurementstructure comprises a measurement structure inlet connected to thefluidic structure to receive the processed biological sample, whereinthe measurement structure comprises an absorbent structure, wherein thechromatographic membrane extends from the measurement structure inlet tothe absorbent structure, wherein the chromatographic membrane comprisesa detection zone, wherein the measurement structure comprises an inletair baffle connected to the front face; wherein the method comprises:placing the biological sample into the sample inlet; controlling therotational rate of the cartridge to process the biological sample intothe processed biological sample using the fluidic structure; controllingthe rotational rate of the cartridge to allow the processed biologicalsample to flow from the measurement structure inlet to the absorbentstructure via the chromatographic membrane, wherein the inlet air bafflereduces the evaporation of the processed biological sample duringrotation of the cartridge; and performing the optical measurement of thedetection zone with an optical instrument.
 2. The method of claim 1,wherein the air inlet baffle is closer to the rotational axis than themeasurement structure inlet and/or wherein the inlet baffle isconfigured for regulating a flow of air over the measurement structureduring rotation of the cartridge about the rotational axis.
 3. Themethod of claim 1, wherein the method further comprises: placing buffersolution at the measurement structure inlet after controlling therotational rate of the cartridge to allow the processed biologicalsample to flow from the measurement structure inlet to the absorbentstructure via the chromatographic membrane; and washing thechromatographic membrane by controlling the rotational rate of thecartridge to allow the buffer solution to flow from the measurementstructure inlet to the absorbent structure via the chromatographicmembrane before performing the optical measurement.
 4. A cartridge foran automatic analyzer, wherein the cartridge is operable for being spunaround a rotational axis, wherein the cartridge comprises: a supportstructure, wherein the support structure comprises a front face; afluidic structure for processing a biological sample into a processedbiological sample, wherein the fluidic structure comprises a sampleinlet for receiving the biological sample; and a measurement structurerecessed from the front face, wherein the measurement structurecomprises a chromatographic membrane, wherein the measurement structurecomprises a measurement structure inlet connected to the fluidicstructure to receive the processed biological sample, wherein themeasurement structure comprises an absorbent structure, wherein thechromatographic membrane extends from the measurement structure inlet tothe absorbent structure, wherein the measurement structure comprises aninlet air baffle connected to the front face.
 5. The cartridge of claim4, wherein the air inlet baffle is closer to the rotational axis thanthe measurement structure inlet.
 6. The cartridge of claim 4, whereinthere is a gap between the air inlet baffle and the measurementstructure inlet.
 7. The cartridge of claim 6, wherein the gap is overthe chromatographic membrane.
 8. The cartridge of claim 4, wherein theinlet baffle is configured for regulating a flow of air over themeasurement structure during rotation of the cartridge about therotational axis.
 9. The cartridge of claim 4, wherein the measurementstructure further comprises a static cover for covering thechromatographic membrane, wherein the static cover comprises anoptically transparent area, wherein the optically transparent area isfixed in alignment with the detection zone of the chromatographicmembrane, wherein the measurement structure further comprises an outletair baffle connected to the front face, and wherein the measurementstructure is vented by the outlet air baffle and the inlet air baffle.10. The cartridge of claim 9, wherein the detection zone has a detectionzone length in a radial direction, wherein the inlet air baffle has aninlet air baffle length in the radial direction, wherein outlet airbaffle has an outlet air baffle length in the radial direction, whereinthe inlet air baffle length and/or the outlet air baffle length is lessthan the detection zone length.
 11. The cartridge of claim 10, whereinone of the outlet air baffle and the inlet air baffle is closer to therotational axis.
 12. The cartridge of claim 9, wherein the detectionzone has a detection zone length in a radial direction, wherein theinlet air baffle has an inlet air baffle length in the radial direction,wherein outlet air baffle has an outlet air baffle length in the radialdirection, wherein the inlet air baffle length and/or the outlet airbaffle length is greater than or equal to the detection zone length 13.The cartridge of claim 12, wherein the inlet air baffle has a firstcontinually smooth surface where the inlet air baffle meets the frontface and/or wherein the outlet air baffle has a first continually smoothsurface where the inlet air baffle meets the front face.
 14. Thecartridge of claim 12, wherein along a circumferential path across thedetection zone the static cover has a first edge and a second edge,wherein the first edge is a first distance from the chromatographicmembrane along the rotational axis, wherein the second edge is a seconddistance from the chromatographic membrane along the rotational axis,wherein the first distance is less than the second distance, whereinadjacent to the first edge the front face is a third distance from thechromatographic membrane along the rotational axis, wherein the firstdistance is greater than the third distance, and wherein at the frontface the static cover is continually smooth between the first edge andthe second edge.
 15. The cartridge of claim 4, wherein the entiremeasurement zone is open to the front face via the first air bafflestructure along a directed path, and wherein the directed path isparallel to the rotational axis.
 16. The cartridge of claim 4, whereinthe measurement structure comprises at least one air pocket adjacent tothe chromatographic membrane, wherein the at least one air pocket iscovered by the front face parallel to the rotational axis.
 17. Thecartridge of claim 15, wherein along a circumferential path across thedetection zone the inlet air baffle has a first air baffle edge and asecond air baffle edge where the inlet air baffle meets the front face.18. The cartridge of claim 17, wherein along the rotational axis thefirst air baffle edge is further from the chromatographic membrane thanthe second air baffle edge.
 19. The cartridge of claim 17, wherein thefront face has an average distance from the chromatographic membranealong the rotational axis, wherein the first air baffle edge and thesecond air baffle edge are further from the chromatographic membranethan the front face along the rotational axis.
 20. A medical system,wherein the medical system comprises a cartridge according to claim 4,wherein the medical system further comprises an automatic analyzerconfigured for receiving the at least one cartridge, wherein theautomatic analyzer comprises a cartridge spinner, an optical instrument,and a controller configured to control the automatic analyzer, whereinthe controller is configured for: controlling the rotational rate of thecartridge to process the biological sample into the processed biologicalsample using the fluidic structure; controlling the rotational rate ofthe cartridge to allow the processed biological sample to flow acrossthe fluidic membrane from the measurement structure inlet to theabsorbent structure via the chromatographic membrane, wherein the inletair baffle reduces the evaporation of the buffer solution; andperforming the optical measurement of the detection zone with theoptical instrument.